The discs of disc brakes, mainly on high performance vehicles, are known to reach a high temperature, thereby generating considerable heat flows towards the brake caliper which tends to be overheated. This overheating may be very dangerous for the brake liquid that may cause the brake to be completely ineffective, in the event it reaches the boiling temperature.
In order to overcome these drawbacks, different solutions are known from the prior art.
For example, DE 3833552 provides pads, wherein the pad plate suitable to be compressed by the caliper piston head comprises radial cavities on the side directly facing said cylinders. The piston head also comprises cavities allowing an air stream to pass through the interface area between the pistons and the pads. This air stream has the purpose of cooling the caliper body and the piston ends. On the other end, the air stream is directly generated by the rotary action of the disc, and by means of ducts carrying the air circulating about the disc towards the pistons from the caliper inner area facing the disc beside the pads housing. However, this air stream is very hot and often not only it does not ensure sufficient cooling, but can be even counter-productive.
Furthermore, JP 62-067337 and JP 61-191535 provide a cooling liquid duct in floating calipers running through the caliper piston and facing the pad plate such as to create such an air flow to lead the heat from the disc to the caliper body.
On the other hand, even the latter solution, though being satisfactory under several aspects, is very complicated to manufacture and assemble in the caliper body, and above all it is not suitable for calipers mounted on high performance vehicles being equipped with pistons provided on both disc sides.
Furthermore, EP 1016804 B1 in the name of the same applicant provides a cooling air channel formed in the thickness of a caliper central bridge; this channel fluidically communicates with the piston heads. This solution, however, tends to weaken the caliper body, which is subjected when breaking to high flexural stress being maximum just at the central bridge.
Furthermore, this channel is often overheated by the heat from the brake disc.